A tunnel linking Watson Island with Interstate 395 to speed truck traffic bound for the Port of Miami has re-emerged with strong support after two years.

The tunnel could cost up to $900 million to build. Any time frame for the project is premature, backers say, but a work schedule would extend beyond a decade.

The plan, now spearheaded by the Florida Department of Transportation’s Turnpike Enterprise, had been put on the back burner for two years while the division reshaped itself to resemble a private-sector enterprise, officials said.

The group is to hire an engineering firm by December to re-evalute and update the project’s two-year-old environmental and cost studies before moving ahead on design, right-of-way and construction phases in the years to come.

Advertising for the engineering bid begins in August, officials said, though a time line for construction has not been established and costs for the engineering study have not been disclosed.

According to Nancy Clements, director of planning & production for Turnpike Enterprise, the division’s new charter eases it of certain policies and procedures and allows it to more aggressively engage in marketing and business development. It was formerly run as a Florida Department of Transportation district.

The change could also streamline future projects under its guidance such as the mammoth port plan, which proposes running a truck tunnel under the bay from Watson Island to the seaport, also with the goal of steering cargo traffic clear of a particularly congested stretch of Biscayne Boulevard, project officials said.

As recently as last week, Port Director Charles Towsley told a group of downtown business leaders that the Watson Island tunnel plan is the only viable solution proposed. He said the project has already undergone years of state and federal review, making it eligible for funding.

Mr. Towsley later voiced skepticism over a more recent proposal to build an underground cargo rail linking the port and Northeast 79th Street.

"That would add years and huge costs to the port’s development," he said.

City of Miami Commissioner Johnny Winton and other downtown advocates hail the rail tunnel plan as a way to move freight through the port without continuing to snarl traffic. It would also mitigate traffic dependence on I-395 and open the way for the city’s vision of a usable livable downtown – a combined value unmatched by any previous proposal, Mr. Winton said last month.

For two decades county and city planners have sought to create a traffic and urban planning solution that could bring into harmony the city’s most valuable resources: the port, the downtown business district and the future performing arts center.

Mr. Towsley said any project other than the truck tunnel would require a minimum of three years and millions of dollars.

"None of the other plans are real," he said. "The truck tunnel is a real project."

The Port of Miami is the top container port in Florida and contributes more than $8 billion and 45,000 jobs to the local economy, port figures state.

"We’re competing against ourselves to find a traffic and transportation solution that benefits the port" and other stakeholders, Mr. Towsley said.

According to the director’s office, cargo traffic currently accounts for 51% percent of the port’s revenue, while passenger traffic makes up the rest.

Mr. Towsley said a cargo traffic solution is long overdue since truckers and freight-forwarders lose money on congestion-related delays. That could lower the port’s competitive standing among other cargo hubs, city and county planners said.